A great variety of filter cartridges embodying pleated filter media potted into end caps is known in the art. Most of those cartridges have a form of support for the media in the form of wire framing, perforated sheeting of various forms, and other means, both internally and externally placed around the filter media and potted into the end caps along with that media.
One of the enduring problems to be solved with these forms of filter cartridges is the tendency of the particles being filtered to hang up in corners and on ledges and other protuberances around the support means and the areas where they touch the filter media.
One attempt to solve this problem was made in the cartridge of Manniso, et al., as described in U.S. Pat. No. 4,878,930, wherein a pleated lower end cap was fitted around the pleated filter medium to match the shape of the pleated filter medium to leave a minimum of protuberance on the cartridge on which the material being filtered could lodge, thus partially blocking or reducing the filtration rate of the surface of the filter medium. Other references cited in that patent outline the art known at that time.
However, even that cartridge does not completely eliminate particle lodgement, only minimizes it. It would be useful to have a cartridge in which there is no lodgement of particles on the surface of the filter medium. This could be quite important in the areas of pharmaceutical and biologicals manufacturer to prevent bacterial growth at the sites of lodged particles, in food processing or manufacture, or in chemical manufacture processes where dust residence time on a cartridge should be short to avoid degradation of the chemical material being filtered.